Many years of research and study have gone into the creation of aerodynamic structures to improve their efficiency and capabilities. Unfortunately, much of this research has been based on underlying scientific principles and theories that have been taken for granted for too long as the only real solution to the problem, constraining the imagination of the designers unnecessarily. For example, the majority of existing airfoils today were designed with Bernoulli's principle in mind. In simple terms, this principle states that when the speed of a fluid increases, the pressure in that fluid decreases. In the case of an airfoil like a wing or the blade of a propeller, the fluid is air, and the airfoil is designed such that the flow of air speeds up when it flows over the top of the airfoil in relation to the speed of the air under the airfoil, decreasing the pressure above and generating lift (because the higher pressure under the airfoil pushes it up into the area of lower pressure).
These Bernoulli-inspired airfoils have worked well enough over the years, but they have their limitations, and there is really no way to make them any more efficient without departing from this traditional design entirely. One limitation on the traditional airfoil design is the speed at which it can be rotated when used on a propeller. These blades are typically rotated at about 2100 to 2500 RPM. If they are rotated much faster, then the tips of the blade start to approach the speed of sound, and once the sound barrier is broken, the resulting shock waves cause disruption in the air flow and reduce the lift generated by the airfoil design. Some aircraft with more powerful engines actually have to use a gear reduction system to make sure the propellers are not rotated too fast to avoid this problem. This is a limitation on the power that could be achieved by today's more powerful engines.
The traditional airfoil design to angle of attack (the angle at which the airfoil is mounted in relation to the direction of travel), airfoil shape, and the speed at which the airfoil is flown. If the traditional airfoil of the prior art is flown at too high of an angle of attack, the flow of air over the top of the airfoil separates from the airfoil surface and lift is greatly reduced. If the airfoil is not shaped properly, the flow of air is disrupted and lift is affected. As the speed of the airfoil through air is increased, its critical angle of attack is decreased; that is, the angle at which the airfoil begins to lose lift is lowered so lift is lost sooner.
Some inventors have tried to improve the traditional airfoil design in the past but with little success. U.S. Pat. No. 4,191,506 by Packham describes one such attempt. Packham describes a propeller design with hollow blades with a triangular cross-section. Unlike traditional airfoil designs, Packham shows the front face of his airfoil pushing into the flow of air with a relatively high angle of attack, and does not depend on a curved top on his airfoil to generate lift. Packham describes the airfoil as being constructed from sheet material such that the blades themselves can be hollow and can help direct air through the blades and out the back side of the rotating blades to help eliminate areas of turbulence behind the blade.
Although the use of a triangular cross section is similar to one aspect of the present invention, that is, in the use of a “reactionary face” that impacts the flow of air and pushes it down, Packham has not shown any data to support the performance of the hollow blades with holes and how they affect air flow and aerodynamics. Finally, Packham's airfoil design is only utilizing one face of the triangular blade to generate lift, while it will be shown that the present invention offers a significant improvement over Packham's airfoil by utilizing both a reactionary front face to push air down (to generate an upward force on the airfoil by Newton's Third Law of Motion) as well as a vacuum producing face on the opposite side of the blade (to generate a region of high negative pressure that pulls the blade upward, reinforcing and increasing the upward lifting force).
Other attempts have been made to improve the traditional airfoil design, but none are as relevant to the present invention as Packham. Other prior art devices describe minor modifications to traditional airfoil designs which are not similar in concept to the present invention, or describe methods of construction, novel materials, etc., not pertinent to the present invention. All of these prior art devices suffer from the same limitations and constraints previously described for traditional, Bernoulli-inspired airfoils above.
What is needed in the art is a novel airfoil design which avoids the constraints and limitations of the traditional Bernoulli-inspired airfoil designs of the prior art, offers significant improvements in performance and lift over the airfoil designs of the prior art, and which can be used on today's conventional aircraft without modification to the aircraft engine or fuselage.